Mid‐manufacturing storage: Antibody stability after chromatography and precipitation based capture steps

Abstract

Antibodies of the IgG2 subclass were captured from the clarified cell culture fluid either by protein A chromatography or by polyethylene glycol precipitation. The captured intermediates were stored as neutralized eluates (protein A chromatography) or in solid form as polyethylene glycol precipitates over a period of 13 months at three temperatures, −20°C, 5°C, and room temperature to compare the capture technologies in regard of the resulting product storability. Monomer content, high molecular mass impurities product loss and changes in the composition of the charge variants were determined at six time points during the storage. At the beginning and end of the study, samples were additionally tested by differential scanning calorimetry, differential scanning fluorimetry, and circular dichroism to determine structural alterations occurring during storage. Protein A purified material was highly stable at all tested temperatures in regard of monomer content and product losses. A transient, acidic isoform was formed during the chromatography step which re‐converted to the main charged variant upon storage within a matter of days. Precipitated antibodies could be stored at −20 or 5°C for 3 months without product losses but afterwards recovery yields dropped to 65%. At room temperature, the precipitated antibody was not stable and degraded within 3 months.

Choline Phosphate-Grafted Nanozymes as Universal Extracellular Vesicle Probes for Bladder Cancer Detection

“…One possible reason that ELISA had lower sensitivity than Pt@CP assay may be due to the weak signal amplification ability of traditional ELISA, which can only identify EVs with a high expression level of CD63, while Pt@CP can be heavily enriched on the surface of the phospholipid bilayer, thus obtaining higher signal amplification ability and decreasing the detection limit. The Ab1 and HRP-Ab2 used in traditional ELISA need to be stored at low temperatures (−20 to −80 °C), and improper storage will affect the detection sensitivity. , As a metal nanomaterial coated by a hydrogel structure, however, Pt@CPs maintain high catalytic activity and stability at room temperature. The prepared Pt@CPs were stored at room temperature for 1, 7, and 28 days to assess the assay reproducibility.…”

“…The Ab1 and HRP-Ab2 used in traditional ELISA need to be stored at low temperatures (−20 to −80 °C), and improper storage will affect the detection sensitivity. 42,43 As a metal nanomaterial coated by a hydrogel structure, however, Pt@CPs maintain high catalytic activity and stability at room temperature. The prepared Pt@CPs were stored at room temperature for 1, 7, and 28 days to assess the assay reproducibility.…”